If you look on the config page, you'll see a "favorite frequency" which designates what your first channels will (try to) be, no matter what other channels are assigned, out of order allows for diversity, your neighbors may have 62,64,63,61 or even through a few others into the mix.

IMO, this version of the firmware shows those DHCP "warnings," but they are not an issue.

I suspect they were there with the older firmware or, at least, the same normal things were happening. We just didn't see them. They show up now at the intervals set by the DHCP server, but nothing bad is happening. It's just business as usual between you and that server.

If they set the intervals at six days, you would see the message every six days, but they would be just as unimportant to your connection as they are now.

If there was a problem with renewing your IP, you would lose connection. You would know there was a problem without even looking at those logs.

If they set the intervals at six days, you would see the message every six days,

Since the firmware update, I noticed that DHCP RENEW warning occurs exactly every 84 hours (3.5 days.).

Your best bet is to schedule a line technician to come out and check outside the lines. Be careful because sometimes when your asking for a technician they send out an installer instead and they sometimes they don't have the training or equipment to do the actual testing on the pole.